1. Field of the Invention
The present invention relates to a light emitting chip including a device chip in which a light emitting layer is formed.
2. Description of the Related Art
Light emitting devices including light emitting diode (LED), laser diode (LD), and so forth have been put into practical use. These light emitting devices normally include a light emitting chip having a device chip in which a light emitting layer that emits light by application of a voltage is formed. In manufacturing of this device chip, first an epitaxial layer (crystal layer) is grown as the light emitting layer in the respective areas partitioned by planned dividing lines in a lattice manner on a substrate for crystal growth. Thereafter, the substrate for crystal growth is divided along the planned dividing lines to be turned to individual pieces. Thereby, the device chips for individual light emitting chips are formed.
In the light emitting chip, in a device chip in which the light emitting layer that emits green or blue light is an InGaN-based material layer, sapphire is generally used as the substrate for crystal growth and an n-type GaN semiconductor layer, an InGaN light emitting layer, and a p-type GaN semiconductor layer are sequentially epitaxially grown over this sapphire substrate. Furthermore, an external lead-out electrode is formed for each of the n-type GaN semiconductor layer and the p-type GaN semiconductor layer.
The back surface side (sapphire substrate side) of this device chip is fixed to a lead frame and the front surface side (light emitting layer side) of the device chip is covered by a lens member. Thereby, a light emitting diode is formed. For such a light emitting diode, improvement in the luminance is considered as an important issue and various methods for enhancing the light extraction efficiency have been proposed before (refer to e.g. Japanese Patent Laid-open No. Hei 4-10670).